says--'When a picture is composed of
the two _extremes_ of hot and cold, we are certain of having employed
the whole strength of the palette; and, if judiciously used to assist
the chiaroscuro, an harmonious union will be kept up between these
opposite qualities, more forcible and splendid than by the _intervention
of middle tint_;' but immediately after he adds--'In producing variety
and contrast, we ought never to lose sight of that imperceptible harmony
arising from the union of two colours in producing a _third_, composed
of both. Whether this be founded on any law existing in optics, or is
merely the result of that sympathy which one colour has to another in
producing harmony, we know not.'

Any colour _too often_ repeated, will destroy its value in proportion to
its repetition; but a continuation of the same colour carried with tact
through the picture, from the highest light to the deepest shade, and
strongly relieved by some colour of a different nature, produces the
beautiful effect so admired in the Dutch and Flemish sketches of Vandyke
and others; arising from the rich brown gradations, brought up to a
'high pitch' of red or yellow, or yellowish white, and subdued by a
little cool grey, merging into blue or green.

Strong colours are generally more usefully applied in supporting the
general whole, than by being employed on the more prominent parts of it.
They are equally useful in focussing the shadows, or in giving them
variety.

If the mixture of many colours be unharmonious and disturbed, perplexity
and confusion will be the result.

When the general character of a picture is of a cool grey, its influence
upon the eye is of a very agreeable description, from its tender and
soft transitions; but its spirit is roused into energy at once by the
introduction of a warm colour; increasing, by its opposition of
character, the harmony of the whole. A red cloak on a figure crossing a
field will explain this.

In Du Fresney I find we 'are not to let two hostile colours meet without
a medium to unite them.' Notwithstanding which, we see the contrary
practised with the greatest success;--blue brought against red, for
instance, the value of each increasing as they antipathize.

The hot and cold colours--the balancing power produced by their
combinations--the arrangement that gives to every object its _place_ and
value, are the principal circumstances that should engage the attention,
when contemplating the work